.banmian  {
width:80%;
border:1px dashed red;
margin-top:10px;
float:right;
clear:right;
height:500px;
}

.banmian .tb_board {

max-height:500px;
width:95%;
height:40px;
padding:5px;

}
.tb_board tr th {

width:40px;
height:40px;
border:1px dashed blue;

}
.tb_board tr th.bt {
width:150px;

}

.tb_board tr  {
height:1%;
width:100%;
border:1px dashed red;
}